1. Field of the Invention
This invention relates to apparatus for perforating a well formation, and more particularly, to an apparatus and method for firing a series of perforating guns from different directions and also to an apparatus and method for orienting perforating guns in a deviated well.
2. Description of the Prior Art
The completion of oil and gas wells by gun perforating is well known in the art. A string of perforating guns is lowered into a well casing cemented into the wellbore, and the perforating gun is positioned adjacent to the formation desired to be perforated. The perforating guns are fired to penetrate the casing and cement and form perforations in the producing formation for recovery of the desired fluids. These perforating guns typically utilize shaped charges to form the perforations.
Typically, a firing head is positioned at the top of the string of guns and is connected to the uppermost gun of a string of guns. A time domain firer (TDF) is positioned between adjacent pairs of guns. When the firing head is triggered, the uppermost gun is then fired, and the time domain firers then cause the string of guns to be fired sequentially from top to bottom. On occasion, the firing sequence is from bottom to top.
In the event of misfiring of guns, it may be necessary to remove the string from the wellbore, and this is a time-consuming and expensive procedure. Therefore, there exists a need for a string of guns which may be fired from one end, but in the event of misfire, may also be fired from the other end with the desired result that all of the guns are fired. In order to do this, it is necessary to have a connection between the guns which will work bi-directionally. The present invention addresses this need by providing a bi-directional explosive transfer apparatus for use between a pair of guns.
Special problems must be addressed in situations involving the completion of highly deviated or horizontal wells. In such cases, it may be difficult or impossible to orient the guns so that they fire in a specific direction. Therefore, guns must be used which fire in substantially all directions, which may not result in the most desirable flow of fluids. The present invention meets this need by providing a string of perforating guns in which the guns are easily oriented in a predetermined position for more directional firing.